Level 40 Fire Rating
Screens for windows and doors shall have a mesh or perforated sheet with a maximum aperture of 2mm, made of corrosion-resistant steel or bronze. Gaps between the perimetre of the screen assembly and the building element to which it is fitted shall not exceed 3mm. The frame supporting the mesh or perforated sheet shall be metal.
Suitable mesh would include bronze or stainless steel.
The requirements for Bal 40 are as follows;
- The risk is considered to be VERY HIGH,
- There is a much increased risk of Ember Attack and burning debris ignited by windborne embers, a likelihood of exposure to a high level of radiant heat and some likelihood of direct exposure to flames from the fire front,
- The construction elements are expected to be exposed to a heat flux not greater than 40 kW/m2.